Multiple neurodegenerative diseases, such as but not limited to Alzheimer's disease (AD), are marked by a progressive decline in cognitive function. The mechanisms underlying these diseases remain unclear, and current interventions for such diseases provide only limited and temporary benefit to a subgroup of patients. Therefore, therapy for neurodegenerative disease represents a large unmet medical need and alternative approaches to therapy are needed. Epidemiologic studies have linked metabolic changes and diseases including obesity, insulin resistance, and diabetes with Alzheimer's disease (AD), Parkinson's disease, and related neurodegenerative diseases, and increasing emphasis is being placed on metabolic processes to try to understand the pathogenesis of these diseases. For example, metabolic hormones including leptin and GLP-1 have recently come into focus as potential targets in the treatment of AD. These hormones have been shown to improve cognitive functions in mouse models of AD.